Optical material and manufacturing method thereof, and light-emitting device, optical isolator, and optical processing apparatus using the optical material

Abstract

An optical material used in a UV-excited yellow light-emitting material and an optical isolator, capable of emitting yellow light stably and highly efficiently even if a large current is fed to obtain the high luminance emission. The optical material used for the UV-excited yellow light-emitting material (2) and the optical isolator (210) is an oxide containing Ce, which is a terbium cerium aluminum garnet type single crystal wherein a part of terbium of a terbium aluminum garnet type single crystal is substituted by cerium. The ratio of number of moles of cerium to the total number of moles of terbium and cerium, namely the composition ratio of cerium, preferably falls within the range from 0.01 mol % to 50 mol %. A part of aluminum may be substituted by scandium or further by any one of terbium, cerium, yttrium, lutetium, ytterbium, and thulium.

Description

TECHNICAL FIELD[0001]The present invention relates to an optical material and a manufacturing method thereof, and a light-emitting device, an optical isolator, and an optical processing apparatus using the optical material.BACKGROUND ART[0002]Demand is increasing for phosphors used for illumination, etc. and for optical materials used for optical parts such as optical isolators. In response to an increasing demand for the use of an LED for illumination in recent years, the brightness of light-emitting diode (LED) has been increasing. A high-luminance LED emits high-intensity light and at the same time dissipates a large amount of heat as a result of feeding of a large current. Since each structural member of an LED is exposed to high-intensity light and disposed in hot places for a long period of time, it must have a high resistance to light and heat.[0003]Typical white light-emitting devices (hereinafter referred to as white LEDs) are roughly classified into the following three typ...

AI Technical Summary

Benefits of technology

The present invention relates to an optical material that can be used as a UV-excited yellow light-emitting material. The material has a stable and high-efficient yellow light emission even at high current densities. The method of manufacturing the material includes preparing a powder raw material containing terbium oxide, scandium oxide, aluminum oxide, and cerium oxide, and pulling up a seed crystal out of a solution obtained by heating. The resulting material can be used as a UV light-emitting device without using a binder, leading to higher efficiency and lower manufacturing costs. The light-emitting device can also include a UV-excited blue light-emitting material to achieve high-luminance white light emission. Additionally, the invention provides an optical isolator material that has a larger Faraday rotation angle and higher transmittance in the wavelength range from 500 nm to 1100 nm. The material can be easily processed into an optical isolator by increasing its diameter.

Problems solved by technology

Meanwhile, it is difficult to adjust the brightness and color tone of the three light-emitting diodes, which complicates circuit configuration and thus increases manufacturing cost.

As a result of exposure of the binder to intense light and high temperature for a long time, the binder degrades and forms color, thus decreasing the light transmittance and the luminous efficiency, which are disadvantages.

Furthermore, when a large current is fed to cause high-luminance emission, not only degradation of the binder but also decrease in characteristics of the phosphors may occur (Non-Patent Literature 2).

Such a white LED also has a problem that its luminous efficiency decreases due to degradation of the binder.

To solve the problem of the degradation of epoxy resin, an attempt was made to use silicone resin instead, but the problem has yet to be solved completely.

However, since gallium oxide, namely a raw material component of TGG, evaporates rapidly, it is difficult to increase the crystal size, improve quality, and ensure reproducibility, which was the reason why the cost cannot be decreased.

However, a single crystal that satisfies the above-mentioned conditions have yet to be obtained, and TGG only has been used in the market.

Meanwhile, since it has an inharmonious melting composition (Non-Patent Literature 3), it is difficult to grow a large crystal, which is why it has yet to be put into practical use.

However, compared to TGG, it is more difficult to increase the size of the single crystal.

However, since the TSLAG single crystal contains Lu, which is expensive, the high cost remains the problem to be solved.

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